Of general conventional ion generators and neutralizers, a conventional neutralizer, for example, applies a high voltage to an acuminate needle-shaped ion generating electrode by a high voltage power supply so as to induce corona discharge, thereby ionizing air. Since the needle-shaped ion generating electrode needs to induce corona discharge efficiently between an opposed ground electrode and itself, a certain insulation distance needs to be ensured. Accordingly, there is a problem that space for constituting ion generation is constrained and thus limitations on size reduction of an efficient ion generator and neutralizer arise.
In addition, the needle-shaped ion generating electrode over long-term use induces corona discharge with difficulty due to influences of buildup of dust and abrasion of physical sputtering, so that ion generating efficiency tends to be reduced. As regards the ground electrode opposed to the needle-shaped ion generating electrode and provided to stabilize discharge, too, buildup of dust is caused and dirt on its surface is advanced because of electrostatic adsorption due to high voltage and physical sputtering of the ion generating electrode. This also results in reduction of ion generating efficiency.
Consequently, a user is constrained to maintenance work to improve ion generating efficiency such as cleaning or replacing the acuminate portion of the needle-shaped ion generating electrode and cleaning the ground electrode and its periphery at regular intervals. Since the maintenance work is the cleaning of an interior of the structure with the acuminate portion, which is also a part where a high voltage is applied, the work is dangerous and troublesome.
For this reason, a tabular ion generating element provided with a discharge electrode and an induction electrode on a tabular but not needle-shaped dielectric has been developed (See Patent document 1 to 3).
Patent document 1: Japanese Unexamined Patent Publication No. 2003-323964
Patent document 2: Japanese Unexamined Patent Publication No. 2003-249327
Patent document 3: Japanese Unexamined Patent Publication No. 2004-105517